1. Field of the Invention
The present invention relates, in general, to data storage networking technology, and more particularly, to a system and method for aggregating storage in a data storage network environment that enhances storage virtualization and that in one embodiment utilizes remote direct memory access (RDMA) semantics on interconnects.
2. Relevant Background
Storage virtualization techniques are rapidly being developed and adopted by the data storage industry. In storage virtualization, the user sees a single interface that provides a logical view, rather than a physical configuration, of the storage devices available to the user in the system or storage network. Virtualization techniques are implemented in software and hardware such that the user has no need to know how storage devices are configured, where the devices are located, the physical geometry of the devices, or their storage capacity limits. The separation of the logical and physical storage devices allows an application to access the logical image while minimizing any potential differences of the underlying device or storage subsystems.
Virtualization techniques have the potential of providing numerous storage system benefits. Physical storage devices typically can be added, upgraded, or replaced without disrupting application or server availability. Virtualization can enable storage pooling and device independence (or connectivity of heterogeneous servers), which creates a single point of management rather than many host or server storage controllers. A key potential benefit of virtualization of systems, including storage area networks (SANs) and network attached storage (NAS), is the simplification of administration of a very complex environment.
The cost of managing storage typically ranges from 3 to 10 times the cost of acquiring physical storage and includes cost of personnel, storage management software, and lost time due to storage-related failures and recovery time. Hence, the storage industry is continually striving toward moving storage intelligence, data management, and control functions outboard from the server or host while still providing efficient, centralized storage management. Present virtualization techniques, especially at the SAN and NAS levels, fail to efficiently manage the capacity and performance of the individual storage devices and typically require that the servers know, understand, and support physical devices within the storage network.
For virtualized storage to reach its potentials, implementation and deployment issues need to be addressed. One common method of providing virtualized storage is symmetric virtualization in which a switch or router abstracts how storage controllers are viewed by users or servers through the switch or router. In implementation, it is difficult in symmetric virtualization to scale the storage beyond the single switch or router. Additionally, the switch or router adds latency to data movement as each data packet needs to be cracked and then routed to appropriate targets and initiators. Another common method of providing virtualized storage is asymmetric virtualization in which each host device must understand and support the virtualization scheme. Generally, it is undesirable to heavily burden the host side or server system with such processing. Further, it is problematic to synchronize changes in the network with each host that is involved in the virtualization of the network storage.
Hence, there remains a need for an improved system and method for providing virtualized storage in a data storage network environment. Preferably, such a system would provide abstraction of actual storage entities from host servers while requiring minimal involvement by the host or server systems, improving storage management simplicity, and enabling dynamic storage capacity growth and scalability.